How To Care for Begonias

When I look over the begonias for sale at my local garden center, I feel like I’m standing on the edge of a giant rabbit hole. There are so many to choose from.

Should I get one for the unusual foliage? For the flowers cascading down from a hanging basket? Or a flat of them to plant as annual flowers? You can do all that and more with begonias.

Types of Begonias

Almost all begonias come from tropical regions. Because they won’t tolerate frost, they’re grown outdoors when the temperature stays above freezing. Some begonias can also be grown as houseplants. Most begonias available today are hybrids. There are thousands of them.

In general, there are three broad groups of begonias:

• Tuberous: These are grown primarily for their flowers, which range from white to red, orange and yellow and variations in between. As their name implies, they’re grown from a root structure called a tuber, which looks like a disk with a hollow dip in one side.
• Rex: Sometimes called rhizomatous begonias, these are known for their striking foliage colors, patterns and shapes. Many also have great flowers. Some gardeners grow these as houseplants.
• Wax: Generally smaller plants with green or bronze leaves, these are usually sold to grow as annual flowers.

When To Plant Begonias

If you live in United States Department of Agriculture Plant Hardiness Zones 10 and 11, you can grow begonias outdoors as perennial flowers. For everyone else, most begonias are annuals.

The best time to buy and plant them is in the spring. Plant outside after your last frost-free date. You can also grow begonias as houseplants year-round. Just protect them from cold temperatures when taking them home.

How To Plant Begonias

Begonias are generally shallow rooted so they don’t need a big, deep container. Make sure the container has drainage holes, and use a general potting mix. Begonias prefer moist, well-draining soil.

Find a well-draining spot with limited sun exposure. All begonias prefer shade and may burn in the afternoon sun. Indoors, begonias do best in indirect sunlight (like from an east window) and high humidity.

If growing begonias from seed, sow them indoors several weeks before your last frost date, following the directions on the seed packet. Note that the seeds are tiny, and you’ll need patience. If you haven’t grown anything from seed before, I wouldn’t start with begonias.

When Do Begonias Bloom?

Many begonias available in spring will already be blooming. To keep them blooming through the summer, periodically pinch off spent blooms. Begonias chosen primarily for their foliage may have smaller blooms that appear later in the summer.

How To Care for Begonias

Keep in mind most begonias are tropical plants.

• Water before the soil completely dries out. Begonias do best in evenly moist soil.
• Fertilize in spring and summer when begonias are growing. Choose a fertilizer with lower nitrogen, formulated to promote more blooms.
• Protect plants from frost in late spring. If overwintering begonias indoors, bring plants inside in late summer before temperatures drop below 60 degrees at night.
• Provide good air circulation to prevent powdery mildew, a plant disease that can discolor leaves and cause them to drop.

Is There a Hardy Begonia?

Yes. Begonia grandis. No surprise, but its common name is hardy begonia! It grows as a perennial in USDA Zones 6 through 9.

Plant it where the soil stays moist, with some morning sun and shade the rest of the day. Hardy begonias should begin blooming by mid-to-late summer with pink flowers. Mulch heavily in late fall. New growth will appear again late in the spring, so don’t lose hope if it doesn’t come up as soon as other perennial plants.

To learn more about begonias, check out the American Begonia Society. Who knows? If you successfully grow the polka dot begonia, one of the most popular ones, you might want to try growing more and even joining the society!